Bioassays with Vibrio fischeri for the assessment of delayed toxicity

The standardized bioluminescence assay with Vibrio fischeri underestimates the aquatic toxicity of chemicals which interfere with metabolic pathways s upporting long term processes like growth and reproduction due to its short incubation time (30 min). Therefore this short term assay was compared wit h two alternative bioassays with prolonged incubation times using the same test organism: the growth inhibition assay (7 h) and the long term biolumin escence assay (24 h). Two sets of compounds were selected to reflect acute and delayed toxicity. The first group comprised pentachlorophenol, dodecylp yridiniumbromide and 3,4-dichloroaniline and the second nalidixic acid, chl oramphenicol and streptomycinsulfate. The effects of compounds with acute t oxicity are determined with similar sensitivity in all bioassays. Substance s with delayed toxicity show only minor or no toxicities in the standardize d short term bioassay but severe effects in both long term bioassays indepe ndent of the parameter used. It is concluded that the standardized short te rm bioluminescence assay exhibits serious limitations for the assessment of aquatic toxicity. The long term bioassays, however, may help to overcome t hese limitations. (C) 2000 Elsevier Science Ltd. All rights reserved.